This invention relates to an air deflector for use in an electric motor, and more particularly to such an air deflector which ensures that air circulated by the cooling fan of a motor mounted internally within the motor on the rotor shaft of the motor moves air longitudinally through the motor for cooling the motor rather than merely circulating the air in circular direction at one end of the motor.
In the operation of an electric motor, a considerable amount of heat is generated within the motor due to losses in the stator, stator windings, bearing friction, and losses in the rotor. Typically, motors are provided with a built-in cooling fan to circulate cooling air over the stator windings, through the air gap between the outer periphery of the rotor and the bore of the stator core, and through hole in the rotor core, and/or stator core as well as spaces between the stator core and shell. If the motor is sufficiently cooled, it will operate more effeciently and will have a longer service life.
In many electric motors, the cooling fans are axial or radial vane fans mounted on the rotor shaft or die-cast-in-place on the ends of the rotor. In certain motor designs, however, it has been found that the cooling air circulated by the cooling fan within the motor was not sufficient to prevent the temperature of parts of the motor from exceeding permissible temperature limits. It was found that although the fan was capable of circulating a sufficient flow of air through the motor, the air circulated by the fan moved in a circular direction within the motor housing adjacent the tips of the rotating fan blades and around the end turns of the stator windings and thus did not flow in a sufficient amount longitudinally through the motor.
In the co-assigned U.S. Pat. No. 3,518,467, a totally enclosed, fan cooled electric motor is disclosed which has auxiliary vanes and shrouds for aiding the flow of cooling air through the motor, for providing increased heat transfer area, and for directing cooling air over the exterior surfaces of the motor. However, these auxiliary vanes and shrouds could not be adapted to many conventional motor designs because of insufficient space adjacent the ends of the stator windings and the end shield. Also, this prior auxiliary vane system required substantial modifications to be made to the motor.